Crackstop structures are formed in dielectric material around an active area of a chip to prevent cracks from propagating into the active area. The crackstop structures can be edge seal structures which prevent ingress of moisture and oxidation into the active area of the chip.
The crackstop structures are typically large metal loop structures. These structures, though, are susceptible to arcing during plasma etch during semiconductor fabrication. Arcing susceptibility is further increased for high resistivity SOI substrates used in RF technologies. For example, high resistivity substrates (used in RF technologies) promote plasma non-uniformities/instabilities leading to arcing and device charging. Arcing damage also often occurs between adjacent metal structures which are not electrically connected. This is particularly a concern in dual rail crackstop structures, which exhibit arcing between adjacent rails or to adjacent metal structures.